He says the Labor Party came up with the conscience vote platform at the last national conference as a "quick fix" to appease the factions.

Mr Howes says he now regrets the role he played in negotiating that compromise.

"I didn't understand at the time that that would lead to the situation that we find ourselves in today where it's unlikely that we would ever see this reform achieved in our national parliament with a conscience vote," he said.

"But I've also had a long think about the nature of what is a matter of conscience and what is a matter of simply the right policy and it's wrong for us to put this down as some issue which is hard for the party to have a defended position on."

He says the ALP will have another debate on the issue at the next national conference due next year.

Mr Howes concedes there are a lot of union members and Labor Party supporters who do not support gay marriage, but he says it is the right thing to do.

"I look at the history of racial discrimination in this country and the important steps that were taken from the end of the Second World War up until 1975 in removing all forms of discrimination from the government against people based on their race," he said.

"It wasn't until the passing of the racial discrimination act by the Whitlam government that all forms of discrimination based on racism were removed.

"I see discrimination based on race and discrimination based on your sexuality as being one and the same."